CRC806-Database Publications Feed (RSS) Publications feed of the CRC806-Database A new cave site at the limestone hogback of Gebel Duwi: Interdisciplinary approaches to study palaeoenvironmental changes in the central Eastern Desert of Egypt The area in the Central Eastern Desert at the limestone hogback of Gebel Duwi near Wadi Sodmein is currently under investigation in the Collaborative Research Centre 806 “Our Way to Europe”, (University of Cologne) in collaboration with the Egyptian Mineral Resources Authority (EMRA). In a joint fieldtrip in 2017 from CRC 806 and EMRA at Wadi Sodmein, a new cave site at Gebel Duwi is thereby firstly investigated with geoscientific methods. The cave has an approximately site of at least 120m and has heights up to 12-15m. A first mapping of the cave was done by the documentation of the main features of the size measurements of the caves size and extent. 2019-02-20T19:44:11+01:00 Eastward-moving convection-enhanced modons in shallow water in the equatorial tangent plane We report a discovery of steady long-living slowly eastward moving large-scale coherent twin cyclones, the equatorial modons, in the shallow water model in the equatorial beta-plane, the archetype model of the ocean and atmosphere dynamics in tropics. We start by constructing analytical asymptotic modon solutions in the non-divergent velocity approximation and then show by simulations with a high-resolution numerical scheme that such configurations evolve into steady dipolar solutions of the full model. In the atmospheric context, the modons persist in the presence of moist convection, being accompanied and enhanced by specific patterns of water-vapour condensation. 2019-02-05T11:54:27+01:00 Reconstruction of Late Pleistocene paleoenvironments in southern Germany using two high-resolution loess-paleosol records Two loess-paleosol sequences from the Heilbronn Basin in southwestern Germany, Frankenbach and Talheim, have been investigated to gain information about environmental conditions during the last interglacial-glacial cycle. Since paleoenvironmental research on terrestrial archives is crucial for a better understanding of past climatic and environmental conditions, the profiles were studied using a multi-proxy approach. Applied methods include the analyses of grain-size distribution, element contents, sediment color, rock magnetism, micromorphology, and black carbon (BC) via benzene polycarboxylic acids (BPCA). The data reveal that the two profiles show large variations in conservation due to their different geomorphologic positions. Moreover, the results imply a subarctic climate with stable conditions during the Middle Pleniglacial (MIS 3) in-situ soil formation phase while the Lower Pleniglacial (MIS 4) was characterized by erosion and reworking of Eemian and Early Glacial (MIS 5) material but also by accumulation of aeolian material during the late Lower Pleniglacial (MIS 4) in Frankenbach. The results further suggest that the Rhine River floodplain has been a major source for the accumulated material in the two profiles, which indicates westerly wind directions during the time of accumulation. The low GSI and U-Ratio of Upper Pleniglacial (MIS 2) sediments, supported by the overall high content of fine material, imply a larger distance to the source area. We give an overview of loess in the Heilbronn Basin and place it in a wider context of loess in Western Europe. 2018-12-18T14:04:25+01:00 The Eltville Tephra (Western Europe) age revised: Integrating stratigraphic and dating information from different Last Glacial loess localities The Eltville Tephra (ET) is an important stratigraphic marker bed in the Western European loess stratigraphy at the boundary between the regional Last Glacial Maximum (LGM) in the sense of the maximum extent of glaciation of the Scandinavian ice sheet and a ‘terrestrial’ LGM with the highest degree of aridity and coldness. Stratigraphic marker beds such as tephra layers are commonly dated at more than one location, and often with more than one method. The sediments surrounding the ET were dated 87 times at 15 localities with different luminescence techniques yielding ages between 13.5 and 49.6 ka. Based on individual sections, the deposition of the ET was supposed to have taken place between 20 and 23 ka. This raises the question of whether a quantitative combination of individual ages can give a reproducible common age, including uncertainties. After screening the dataset and applying selection criteria, a Bayesian resampling approach is applied to obtain a common age consistent with a high percentage of observations from multiple localities. Four new luminescence ages bracketing the ET and two ages directly generated from the tephra horizon are presented and combined with all available data. The 1σ age range of the Bayesian age modelling yields a deposition age between 23.2 and 25.6 ka, which is in excellent agreement with two new luminescence ages from the tephra of 24.1 ± 1.9 ka (quartz) and 24.3 ± 1.8 ka (pIRIR290) and a peak of volcanic minerals in the Dehner Maar core around 24.3 ka. This age is clearly older than previously suggested for the ET volcanic eruption, but fits better with stratigraphic and paleoenvironmental evidence. Therefore, the ET was deposited during phases of strong aeolian activity of the Greenland Stadial 3. Additionally, for the first time, a correlation can be made between the ET and tephra layers recognized in the Eifel Maar lake cores. 2018-12-18T13:57:38+01:00 The MIS 3/2 transition in a new loess profile at Krems-Wachtberg East - A multi-methodological approach Local to regional paleoenvironmental reactions to past climate changes are preserved in loess-paleosol sequences (LPS). In order to extract this information we used a multi-methodological approach in the Upper Paleolithic site of Krems-Wachtberg East in Lower Austria. Detailed field studies and high-resolution geochemical, colorimetric, and granulometric analyses help to understand the interplay between soil formation, loess accumulation, and surface processes. In comparison to the main profile/excavation of Krems-Wachtberg 2005–2015 it can be stated that OSL- and 14C-ages as well as the (archeological) stratigraphy of both profiles are comparable. However, pedogenic features are more evident at Krems-Wachtberg East. The new investigations show that well-established weathering indices do not clearly trace interstadial soil formation in the studied profile. Apart from this fact, single specific elements like Fe and Mg react more sensitive to initial pedogenic processes. Weak pedogenesis can further be evidenced by quantitative spectrophotometric results. The latter is also capable of refining and supporting the stratigraphy/pedology based on field analyses. As a general rule, next to loess also initial soil horizons of the MIS 3 are remarkably rich in primary carbonates indicating that soil formation took place in an alkaline environment. Due to the fact that hydrolysis of feldspars could not clearly be detected by the application of pedochemical indices, soil formation was probably limited to the oxidation of iron bearing minerals and weak carbonate leaching. These phases of favorable climatic conditions in terms of pedogenesis were terminated by increasing dust input towards the onset of MIS 2. The eolian deposits are overprinted during reducing conditions in soils and/or modified by colluvial processes. Altogether, weak pedogenesis can be reliably detected using a multi-methodological approach which leads to enhanced paleoenvironmental interpretations. The OSL-ages put the profile in a range of ∼41 to 30 ka. We present a tentative correlation of the studied loess profile to the record of the North Greenland Ice Core Project (NGRIP) for the part of the profile where OSL and 14C complement each other. 2018-12-18T13:27:32+01:00